This application relates to the respective flow areas between a fan and a pair of compressor sections in a gas turbine engine having three turbine rotors.
Gas turbine engines are known and, typically, include a fan delivering air into a compressor. The air is compressed in the compressor and delivered into a combustion section where it is mixed with fuel and ignited. Products of this combustion pass downstream over turbine rotors driving them to rotate.
In one known type of gas turbine engine, there are three turbine rotors. A highest pressure turbine rotor and an intermediate pressure turbine rotor each drive compressor stages.
The high pressure compressor rotor has typically been relied upon to develop a good deal of an overall pressure ratio across the two compressor rotors. The downstream end of this high pressure compressor rotor is a challenging location within the gas turbine engine, as it must be able to withstand the temperatures and stresses it will see due to these high pressures.
A fan drive turbine has been provided which drives a fan. Historically, the two rotated at a common speed. More recently, it has been proposed to include a gear reduction such that the fan can rotate at slower speeds than the fan drive turbine rotor.